Photophysical dynamics of the efficient emission and photosensitization of [Ir(pqi)(2)(NN)](+) complexes

Author(s)

Zanoni, Kassio P. S. ^{[1, 2]} ; Ito, Akitaka ^{[3, 4]} ; Gruner, Malte ^[1] ; Iha, Neyde Y. Murakami ^[2] ; de Camargo, Andrea S. S. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, Lab Espect Mat Funcionais, BR-13566590 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Lab Fotoquim & Conversao Energia, BR-05508900 Sao Paulo, SP - Brazil

^[3] Kochi Univ Technol, Sch Environm Sci & Engn, Kochi 7828502 - Japan

^[4] Kochi Univ Technol, Res Ctr Mat Sci & Engn, Kochi 7828502 - Japan

• Document type: Journal article
• Source: DALTON TRANSACTIONS; v. 47, n. 4, p. 1179-1188, JAN 28 2018.
• Web of Science Citations: 7

Abstract

The photophysical dynamics of three complexes in the highly-emissive {[}Ir(pqi)(2)(NN)](+) series were investigated aiming at unique photophysical features and applications in light-emitting and singlet oxygen sensitizing research fields. Rational elucidation and Franck-Condon analyses of the observed emission spectra in nitrile solutions at 298 and 77 K reveal the true emissive nature of the lowest-lying triplet excited state (T1), consisting of a hybrid (MLCT)-M-3/LCIr(pqi) -> pqi state. Emissive deactivations from T-1 occur mainly by very intense, yellow-orange phosphorescence with high quantum yields and radiative rates. The emission nature experimentally verified is corroborated by theoretical calculations (TD-DFT), with T-1 arising from a mixing of several transitions induced by the spin-orbit coupling, majorly ascribed to (MLCT)-M-3/LCIr(pqi)-> pqi and increasing contributions of (MLCT)-M-3/LLCTIr(pqi) -> NN. The microsecond-lived emission of T-1 is rapidly quenched by molecular oxygen, with an efficient generation of singlet oxygen. Our findings show that the photophysics of {[}Ir(pqi)(2)(NN)]{[}PF6] complexes is suitable for many applications, from the active layer of electroluminescent devices to photosensitizers for photodynamic therapy and theranostics. (AU)

• FAPESP's process: 16/07706-4 - Nanocrystalline luminescent materials: new chemical concepts for energy conversion and sustainability
• Grantee: Kassio Papi da Silva Zanoni
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/24118-6 - Study of light emitting nanoparticles (upconverting nanophores) for biomedical and biotechnological applications
• Grantee: Malte Christian Gruener
• Support Opportunities: Scholarships in Brazil - Post-Doctoral